Yttria stabilised zirconia xerogels are heat treated to temperatures of 1000°C, and the evolving structures are analysed using anomalous small-angle X-ray scattering (ASAXS) across two absorption edges. Homogeneous nanocrystals (~10 nm in size) begin to grow at temperatures above 390°C for pure YSZ, whilst the presence of a silica matrix inhibits nucleation until 780°C. Anomalous effects have shown the zirconia plays the dominant role in crystal growth, and varying concentrations of yttria do not affect the nucleation temperatures, or average size of the individual particles. The difference between scattering factors, necessary for accurate ASAXS analysis, is also investigated. Relations for this analysis were derived from X-ray absorption spectra - conducted as part of the small-angle scattering investigations.